This invention relates to a process which utilizes an axial compressor which integrates into itself a compressor and expansion engine.
A schematic diagram of an air conditioning system as known in the prior art is shown in FIG. 1. Air conditioning systems use the process of using a compressor 10 to compress a gas to high pressure 11 which makes it hot. This hot gas 11 is then cooled down in a heat exchanger or condenser 12. Generally a fan 14 forces cool air over or through the heat exchanger 12 to produce a cooled gas 13. The cooled gas 13 then passes through a throttling valve 16 which allows the cooled gas 13 to expand to a low pressure which creates a cold gas 17. The cold gas 17 then passes through another heat exchanger or evaporator 18, where a second fan 20 forces air over or through the evaporator 18 so that heat can be removed from the intended environment such as an automobile, home air conditioner, refrigerator, etc. The exiting low pressure gas 21, now warmed, is returned to the compressor 10 where the cycle is repeated.
In the air conditioning system illustrated in FIG. 1, cooling took place by expanding the gas from a high pressure to a low pressure through the throttling valve 16. This is an inefficient process, producing the desired cooling effect, but with no work being done during the expansion process.
It is commonly known to use air to power various devices. For example, in an auto shop air wrenches are used to remove lug nuts from wheels. Air tools are used because they are compact, powerful, reliable and, unlike electric tools, remain cool during use. If one holds his hand over the air tool exhaust he would feel the cool air exiting the tool. This process duplicates precisely the effect employed in common air conditioning systems, shown in FIG. 1 above.
As can be seen in FIG. 2, by replacing the throttling valve 16 of FIG. 1 with an expansion gas operated motor 22, the same cooling will be achieved but with positive work being produced. This is accomplished by means of a mechanical coupling 24 connecting the expansion engine 22 to the compressor 10. This energy can be used to help drive the compressor 10, thereby reducing the system energy requirements significantly. Energy savings on the order of 30% are not unreasonable.
The problem in implementing the system as illustrated in FIG. 2 is the difficulty in mechanically coupling the separate expansion device 22 to the compressor 10. Further, the work energy recovery is not as hoped for due to the lower operating pressure levels used in typical air conditioning systems. However, the air conditioning community has now banned fluorocarbons from the environment and is moving rapidly away from the use of low pressure hydrofluorocarbons and to high pressure CO2 gas refrigeration. The use of high pressure CO2 enhances the performance advantages expected from expansion devices. Energy savings of over 35% have been achieved with such test systems. The problem of coupling or returning that energy to the compressor system is still unresolved.